public bool Intersects(FastBounds2D b)
        {
            var gap =
                (max_x < b.min_x || b.max_x < min_x) ||
                (max_y < b.min_y || b.max_y < min_y);

            return(!gap);
        }
 public void Encapsulate(FastBounds2D fb)
 {
     Encapsulate(fb.min_x, fb.min_y);
     Encapsulate(fb.max_x, fb.max_y);
 }